The present invention relates to the uniform application of a fluid for treatment of a roll in a rolling mill or the like, for example, hot or cold rolling of a strip and more particularly, to employing a header for controlling the placement of the coolant across a transverse portion of the roll used for rolling hot strip to rapidly, substantially, and uniformly remove the heat built-up from successive portions of the roll leaving contact either with the heated material being rolled and/or with an associated back-up roll in a multi-high mill.
Presently, headers for applying coolant to the rolls are generally employed to prevent damage to the surface finish of a roll or to thermally control the crown of a roll of a rolling mill. Efficient cooling in the rolling system particularly with regard to the work rolls has several advantages, such as: greater thermal stability; increased life of the roll and wearing thereof, and other mill components; better shape control of the product being rolled; and the reducing of the rate and severity of the surface failure of the work roll which failure is due to thermal fatigue.
Several types of headers are known in the art, such as those employing spray nozzles as disclosed in U.S. Pat. Nos. 3,994,151 and 4,247,047, or a series of discharge slots as disclosed in U.S. Pat. No. 2,811,059. The spray nozzles of the first two U.S. patents deliver high pressure, high volume coolant which then fans out overlapping with the streams of an adjacent nozzle. This overlapping condition results in a non-uniform cooling of the rolling surface and furthermore, the impingement of the sprays against the roll surface is so great that the coolant drops are caused to rebound before meaningful cooling can even occur. In some forms of this type, the sprays are moved further away from the roll surface in an attempt to alleviate the foregoing problems, but this creates a distance between the adjacent streams of the sprays which frequently happens in the first mentioned form due to the nozzles becoming clogged, and therefore, a section of the roll does not receive any coolant.
U.S. Pat. No. 2,811,059 discloses employing a header having a subdivided slot for discharging coolant under high pressure against the surface of a work roll, the discharge apparatuses being arranged on the entry side of the rolling mill stand very closely located to the work rolls to attempt to cool a roll section prior to its contact with a workpiece.
While employing a series of slots instead of circular opening nozzles, the slots are spaced apart and the fluid is understood to be under relatively high pressure so that not only is the coolant applied on the entry side of the roll, but the construction of the slots, the placement of the header, and the pressure of the fluid will not produce enveloping coverage of the fluid, uniform in extent and thickness over the entire surface of the roll at the most advantageous location to give optimized cooling.
Other problems arise with these high pressure sprays or flows in that the violent rebounding of the coolant molecules causes the grease and oil in the bearings of the rolls to be washed away resulting in damage to the spindles of the rolls.
Apparatuses for applying low pressure, nonturbulent, coherent curtain walls of fluid to a surface for cooling thereof have been disclosed in a patent application for cooling rod, bearing U.S. Ser. No. 529,822 filed Sept. 6, 1983, and in U.S. Pat. No. 4,047,985 issuing on Sept. 13, 1977 for symmetrically cooling the top and bottom surfaces of a strip, both inventions being that of the present inventor, J. I. Greenberger. Also, such apparatuses for cooling strip have been disclosed in U.S. Pat. No. 4,403,492 issuing on Sept. 13, 1983; in U.S. Pat. No. 4,210,288 issuing July 1, 1980; and in recently issued patent application bearing U.S. Ser. No. 367,350 filed Apr. 12, 1982, the inventor being J. C. Dobson and/or Thomas Hope in all three cases. These apparatuses are designed to adapt to the particular environment in which they are used and for a particular product to be cooled and cannot and would not successfully be utilized in the same manner as the present invention.